1. Field of the Invention
This invention relates to a battery device for loading on a moving body, such as a car or a vessel. As an example, the invention relates to a battery device that may be loaded with advantage on a hybrid system car where the battery and an internal combustion engine are selectively switched so as to be used alternatively as a driving source.
2. Description of Prior Art
For coping with the problems of resources and environment, an electric car, having a battery device as a driving source, is attracting attention as substitution for a gasoline engine car or a diesel engine car. Up to now, a lead accumulator has been used as a driving source for the car electric system. Thus, in the development of an electric car, the battery device used was basically a lead accumulator. However, in order to realize a practically satisfactory running distance by charging only once, an excessively large size or weight of the battery device poses a problem in connection with the use of the lead accumulator.
For this reason, attempts are being made for developing a practically usable hybrid car system where switching is suitably made between an electric motor and a conventional internal combustion engine depending on the running conditions to suppress the excessive size of the battery device furnishing the power to the motor as well as to achieve energy saving and cleanness in operation. On the other hand, attempts are being made to use a lithium ion secondary battery in place of the conventional lead accumulator, in view of the high performance and lightness in weight of the lithium ion secondary battery, in consideration that a higher voltage of tens to hundreds of volt, a higher energy density and higher output specifications are demanded of the car battery device.
For example, in Japanese Laying-Open Patent H-9-86188 entitled xe2x80x9cBattery Device for Electric Carxe2x80x9d, there is disclosed a car battery device in which a large number of lithium ion secondary batteries are accommodated in a large number of separate chambers in a battery casing split into an upper half and a lower half, the abutting surfaces of which are formed as-one with a large number of semi-cylindrical ribs. The battery casing is completed on unifying the upper and lower halves together. At this time, a large number of separate chambers are formed by facing ribs for accommodating columnar-shaped lithium ion secondary batteries.
The ribs are formed with several grooves at several longitudinal points. In these grooves, an adhesive for cementing the lithium ion secondary batteries is charged into these grooves. On unifying the upper and lower halves together to complete the battery casing, the respective lithium ion secondary batteries are sandwiched between the neighboring ribs and are secured in position by the adhesive applied at several longitudinal points.
In the above-described prior-art car battery device, the respective lithium ion secondary batteries are protected against severe vibrations or shocks by being housed in the separate chambers defined by arcuate partitioning wall sections provided in the battery casing and by being secured by an adhesive applied at the several longitudinal points. Therefore, if, in the prior-art car battery device, an excessive amount of the adhesive is charged into a groove in the partitioning wall section, the lithium ion secondary battery accommodated therein is floated so that it is not cemented fixedly to the inner periphery of the partitioning wall section. In the prior-art car battery device, the lithium ion secondary batteries tend to be moved due to vibrations or the like, under the low bonding force caused by such floating, thus raising the problem of insufficient contact. Thus, in the above-described prior-art car battery device, charging of the adhesive needs to be preformed under meticulously controlled conditions to apply the adhesive evenly in the large number of grooves, thus lowering the operating efficiency.
Moreover, in the prior-art car battery device, a large number of lithium ion secondary batteries are accommodated in the battery casing, and are cemented in position with an adhesive. Thus, in the prior-art car battery device, a large quantity of the adhesive is used and a large number of process steps are involved in charging the adhesive to the grooves, with the result that the production cost tends to be raised. Moreover, the prior-art car battery device suffers from the problem of increased overall weight due to the use of a large quantity of the adhesive.
In addition, in the prior-art car battery device, the lithium ion secondary batteries are accommodated in one of the battery casing halves, after which the other battery casing half is bonded to the firstly stated half to perform the processing of the next process step. Thus, the prior-art car battery device suffers from the problem that extremely labor-consuming operations of accommodating a large number of lithium ion secondary batteries and assembling the battery casing halves are required, while the adhesive needs to be cured over a prolonged time, thus lowering the efficiency.
On the other hand, in the prior-art car battery device, the lithium ion secondary batteries are manufactured by separate steps and accommodated in the battery casing. In the prior-art car battery device, operating tests are conducted following the above-described assembling operations. If malfunctions in certain lithium ion secondary batteries are found by this operational test, the entire car battery device has to be rejected because considerable difficulties are met in replacing the malfunctioning lithium ion secondary batteries cemented in position in the battery casing by the adhesive.
In the car battery device, a variety of detection sensors, such as a voltage sensor or a temperature sensor, are provided to assure normal and safe operations. The car battery device is constructed so that the lithium ion secondary batteries are checked for unusual heat evolution by e.g., a temperature sensor and, if such unusual heat evolution is detected, an unusual situation detection signal is sent from the temperature sensor to a controller to execute a pre-set control operation.
In the prior-art car battery device, a temperature sensor is cemented on the outer periphery of the pre-set lithium ion secondary batteries with an adhesive and the entire assembly is housed in this state in the battery casing. The prior-art car battery device thus suffers from the problem that there is required a process step of holding the temperature sensor by e.g., a holding jig on the outer periphery of the lithium ion secondary batteries, until the adhesive is cured, thus again lowering the efficiency. Also, the prior-art car battery device suffers from the problem that stable detection operations cannot be realized because no measures are used to control the mounting position of the temperature sensor on the lithium ion secondary battery.
It is therefore an object of the present invention to provide a battery device for loading on a moving body where a large number of secondary batteries can be efficiently accommodated and fixedly cemented in position in the battery housing section in a modular casing, malfunctioning batteries, if any, can be readily exchanged and unusual heat evolution can be detected in stability.
For accomplishing the above object, the present invention provides a battery device for loading on a moving body including a modular casing having a battery housing section therein and a large number of terminal openings, an outer casing member for housing the modular casing in an inner housing spacing thereof, and a large number of secondary batteries housed in the inner housing spacing so that terminal portions thereof are exposed to outside through the terminal openings. The modular casing and/or the outer casing member is formed with a mounting portion for mounting the modular casing to the outer casing member so that a gap is formed between outer and inner peripheral parts thereof facing each other.
The present battery device for loading on a moving body has a dual casing structure of an outer casing member and a modular casing. By accommodating the set of secondary batteries in the battery housing section such as to maintain a gap between the outer casing member and the modular casing to accommodate the set of secondary batteries in the battery housing section, it is possible to suppress the effect of radiant heat from the road surface or rapid changes in temperature on the set of secondary batteries as well as to suppress loads such as local external force applied to the modular casing. By such structure of the battery device for loading on a moving body, the set of secondary batteries exhibits stable performance characteristics, while being protected mechanically. In the battery device for loading on a moving body, a control unit for controlling the set of the secondary batteries, for example, is mounted in this gap to improve spatial efficiency.
The battery device for loading on a moving body includes, in the modular casing, an air suction unit for supplying cooling air to the battery housing section, and an air exhaust section for exhausting the cooling air from the inside of the battery housing section, in addition to the battery housing section. The secondary batteries are accommodated in the battery device so that the terminal portions of the batteries are exposed to outside through the terminal openings. The secondary batteries are secured at both ends thereof by an adhesive to the terminal openings so that a gap is defined between the outer peripheries thereof and the battery housing section. The gap between the outer peripheries thereof and the battery housing section provides a flow duct for the cooling air in the battery housing section to accelerate heat radiation of the secondary batteries to realize efficient cooling.
The battery device for loading on a moving body also includes a pair of modular casings housed in an outer casing member. There are formed a suction duct half and an exhaust duct half constituting a suction duct and an exhaust duct in the combined state of the modular casings. With the modular casing housed in the outer casing member, the suction and exhaust ducts are protruded in the shielded state from the outer casing member. The paired modular casings of the battery device for loading on a moving body include duct spatial half sections communicating with the suction and exhaust duct halves. In the combined state of the two modular casings, the duct halves constitute a distributing spatial section for distributing the cooling air supplied from the suction duct to the battery housing section of each modular casing and an exhaust spatial section for exhausting the cooling air from the battery housing sections to the exhaust duct.
With the battery device for loading on a moving body, the cooling air supplied via the suction duct into the battery housing section is discharged via the exhaust duct to efficiently cool the secondary batteries. The cooling air is allowed to flow via the gap through a space between the outer casing member and the modular casing to accelerate the hear radiating action. Also, the control unit arranged via this gap is cooled to develop a stable output as well as to realize stable control operations. Since a set of the suction and exhaust structures is constituted for a pair of modular casings, the overall structure may be simplified to reduce pressure loss to supply or exhaust the cooling air to realize efficient cooling.
There are defined recesses at the four comers of the modular casing for constituting a spatial section for procuring a flow duct for cooling air in the interior of the outer casing member. With the battery device for loading on a moving body, stagnant flow of cooling air in the interior of the outer casing member is eliminated to assure efficient cooling. In the battery device for loading on a moving body, since the recesses serve for guide spatial sections for laying the cords or as hand support in transporting the modular casing, it is possible to realize reduction in size and ease in handling.
In the battery device for loading on a moving body, the secondary batteries are housed in plural tiers in the battery housing section, whilst the inner surface of the battery housing section is arcuately shaped to define a gap of substantially equal shape and size around the outer periphery of the secondary batteries. In the battery device for loading on a moving body, the secondary batteries are arrayed with an offset of one-half the battery diameter in the left-and-right direction in the vertically neighboring tiers, with the number of the secondary batteries decreasing progressively in a direction from upper to lower tiers.
In the battery device for loading on a moving body, the cooling air is allowed to flow uniformly along the outer periphery of the secondary batteries in the battery housing section to cool the secondary batteries substantially uniformly irrespective of the housing positions. In the battery device for loading on a moving body, there is produced a turbulent flow of the cooling air on the arcuate inner surface of the battery housing section to promote heat transmission to the modular casing to effect efficient cooling. In the battery device for loading on a moving body, the secondary batteries are efficiently housed in the battery housing section to realize size reduction by efficient space utilization. On the other hand, the cooling air is allowed to flow at an even flow rate.
In the battery device for loading on a moving body, an urethane-based adhesive, a silicon-based adhesive or a modified silicon-based adhesive is used as an adhesive for coupling or bonding the outer casing member, modular casing or the secondary batteries. The connecting portions of the battery device for loading on a moving body are constructed by abutting structures of irregularities, whilst an excess adhesive is allowed to flow out to inside.
Thus, in the battery device for loading on a moving body, the connecting portions may be fixedly bonded since the adhesive retains its elastic properties even in the cured state of the adhesive. On the other hand, the connected state may be positively kept despite application of vibrations or shock or in case of dimensional tolerances or changes in temperature. With the battery device for loading on a moving body, water-tightness may be maintained reliably to improve the operational reliability.
In the battery device for loading on a moving body, the control unit is mounted on the modular casing by fitting a fitting weld portion to an elongated mounting opening formed in the circuit substrate and by heat fusing the weld portion. In the battery device for loading on a moving body, the elongate opening operates to release the mechanical stress produced in the mounting site caused by large changes in temperature or humidity due to difference in thermal expansion coefficient between the modular casing and the circuit substrate, so that it is possible to maintain the fixed state of the control unit as well as to prevent its destruction.
The battery device for loading on a moving body has the dual structure of the outer casing member and the modular casing. The secondary batteries are housed in the battery housing section in such a manner that a gap is defined between the outer casing member and the modular casing. Therefore, in the battery device for loading on a moving body, it is possible to suppress adverse effects of the radiant heat from the road surface or rapid temperature changes on the secondary batteries, as well as to suppress application of local external force on the modular casing. Thus, the set of secondary batteries manifests stable performance characteristics while being protected mechanically. With the battery device for loading on a moving body, it is possible to improve the spatial efficiency by mounting the control unit controlling the set of secondary batteries on the modular casing in the spacing provided by the gap. In the battery device for loading on a moving body, the modular casing is includes, in addition to the battery housing section, a suction unit for supplying the cooling air to the battery housing section, and an exhaust section for exhausting cooling air from the interior of the battery housing section. The secondary batteries are housed in the battery loading device so that terminal portions of the secondary batteries face the outside via the terminal opening, in such a manner that both ends of the secondary batteries are bonded to the terminal openings by an adhesive as a gap is maintained between the outer peripheries and the battery housing section. In the battery device for loading on a moving body, the secondary batteries are fixedly bonded in position in the battery housing section by an adhesive, whilst the flow duct of the cooling air is maintained in the battery housing section by the gap between the outer peripheries and the battery housing section to accelerate heat dissipation of the secondary batteries to assure efficient cooling.
Also, in the battery device for loading on a moving body, the paired modular casings are housed in the outer casing member. There are provided a suction duct half and an exhaust duct half which, in the assembled state of the modular casings, constitute a suction duct and an exhaust duct. In the state the modular casings are housed in the outer casing member, the suction and exhaust ducts are projected in the shielded state from the outer casing member. In the battery device for loading on a moving body, duct spatial half sections communicating with the paired modular casings are formed in the paired modular casings. In the combined state of the modular casings, there are defined a distributing spatial section for distributing the cooling air supplied from the suction duct to the battery housing section of each modular casing and an exhaust spatial section for exhausting the cooling air from each battery housing section to the exhaust duct. In the battery device for loading on a moving body, the cooling air supplied via the suction duct into the battery housing section is discharged from the exhaust duct to effect efficient cooling of the secondary batteries. In the battery device for loading on a moving body, the cooling air flowing via the gap through the space between the outer casing member and the modular casing accelerates heat dissipation. Moreover, cooling unit arranged via this gap is also cooled to develop a stable output as well as to effect a stable control operation. In the battery device for loading on a moving body, since the set of the suction and exhaust structures is constituted for the paired modular casings, the overall structure is simplified. Moreover, pressure loss can be decreased for each battery housing section to supply and discharge the cooling air to effect efficient cooling.
In the battery device for loading on a moving body, the spatial sections for holding the flow duct of the cooling air are constituted by the recesses provided at the four corne4rs of the modular casing. In the battery device for loading on a moving body, these spatial sections eliminate stagnant air flow sites in the interior of the outer casing member to realize efficient cooling. Since the recesses act as hand support for laying the cords or transport of the modular casing, it is possible to reduce the size as well as to improve ease in handling of the device.
In the battery device for loading on a moving body, secondary batteries are housed in plural tiers in the battery housing section, the inner surface of which is arcuately formed to leave a gap of approximately the same size and shape on the outer periphery of the secondary batteries. In the battery device for loading on a moving body, the battery housing section is formed as a trapezoidal spatial section in which the secondary batteries are housed in such a manner that the batteries are offset by one-half the diameter in the left-and-right direction between two neighboring tiers, with the numbers of the batteries in the respective tiers decreasing in a direction from upper to lower tiers. In the battery device for loading on a moving body, the cooling air is allowed to flow uniformly along the outer periphery of the secondary batteries in the battery housing section to cool the secondary batteries substantially uniformly irrespective of the housing positions. In the battery device for loading on a moving body, there is produced a turbulent flow of the cooling air on the arcuate inner surface of the battery housing section to promote heat transmission to the modular casing to effect efficient cooling. In the battery device for loading on a moving body, the secondary batteries are efficiently housed in the battery housing section to realize size reduction by efficient space utilization. On the other hand, the cooling air is allowed to flow at an even flow rate.
In the battery device for loading on a moving body, an urethane-based adhesive, a silicon-based adhesive or a modified silicon-based adhesive is used as an adhesive for coupling or bonding the outer casing member, modular casing or the secondary batteries. The connecting portions of the battery device for loading on a moving body are constructed by abutting structures of irregularities, whilst an excess adhesive is allowed to flow out to inside. In the battery device for loading on a moving body, since the adhesive retains its elastic properties even in a cured state, the bonded sites are secured strongly, whilst the bonded state may be reliably maintained against vibrations or impact regardless of the dimensional tolerances or changes in temperature. The battery device for loading on a moving body exhibits extremely high water-tightness to improve the reliability.
In the battery device for loading on a moving body, the control unit is mounted on the modular casing by fitting and thermally fusing a fitting weld portion in an elongate mounting hole bored in a circuit substrate. In the battery device for loading on a moving body, the elongate opening operates to release the mechanical stress produced in the mounting site caused by large changes in temperature or humidity due to difference in thermal expansion coefficient between the modular casing and the circuit substrate, whereby it is possible to maintain the fixed state of the control unit as well as to prohibit its destruction.